Why Blender Rendering and Previewing Wrong Colors in Video Editor?
Eventually, I fixed the problem. As I said, I'm quite new and haven't got a comprehensive knowledge about the panels and settings in Blender.

Instead of deleting the question, I will answer it and help the other people who have encountered this problem. Let me explain how I solved it briefly:



Under the "Render Context Tab", there is a setting called "Color Management". As a default, its "View Transform" is "Filmic", let's change it to "Standart" or "Raw". The problem will be fixed in this way.

In a nutshell, Render Context -> Color Management" -> View Transform -> Standart.